1. Field of the Invention
The present invention relates to a vertebral column replacement body or spacer with first and second anchoring sides each facing in the mounted or implanted state of the body an adjacent vertebra, wherein each anchoring side has a tooting for ensuring that displacement in the ventral or dorsal directions is safely prevented.
2. Description of the Related Art
In conventional vertebral column replacement bodies of this type, as disclosed, for example, in DE GM 297 03 043, the two anchoring sides of the approximately parallelepiped-shaped body have a fixed predetermined distance between each other. Consequently, the possibilities for using this replacement body or spacer are limited.
Therefore, it is the primary object of the present invention to further develop the conventional vertebral column replacement body in such a way that it can be adjusted to the existing conditions of use.
In accordance with the present invention, the vertebral column replacement body has two body elements which are slidingly guided relative to each other and transversely of the anchoring sides, wherein, after a desired relative position has been reached, a first body element can be braced against the second body element by radially widening the first body element.
Because of the infinitely variable length adjustment capability of this vertebral column replacement body or spacer, the replacement body or spacer can be adapted in an optimum manner to the locally existing conditions of a patient.
It has been found to be very useful for this purpose if the first body element has two, or preferably several, segments extending approximately parallel to the axis away from the first anchoring side, wherein the segments are bendable relative to each other in the radial direction by means of a tightening screw which acts transversely of its direction of extension.
In a preferred embodiment of this vertebral column replacement body, the second body element has a wall extending away from the second anchoring side, wherein the segments of the first body element can be placed in tight contact with the wall by means of the tightening screw.
In accordance with a particularly advantageous feature, the single tightening screw extends radially through a threaded bore of a segment of the first body element and the tightening screw acts with its front end on the other segments of the first body element.
In accordance with another advantageous further development of the vertebral column replacement body according to the present invention, a particularly uniform force application and, thus, bracing of the two body elements, is achieved by providing three segments in the first body element and by having the tightening screw extending through one segment protrude with its front end into the area between the two other segments in order to simultaneously apply a radial force.
In accordance with a useful feature, the first body element is constructed in the form of a cylindrical cup which is divided into three segments of equal size by providing slots extending parallel to the axis and with the same angular spacing up to below the edge forming the first anchoring side, wherein the first segment has the threaded bore which is directed towards the slot between the two other segments. The bottom of the cup advantageously has a thickness which is greater than the diameter of the threaded bore for receiving the tightening screw and, thus, is significantly greater than the wall thickness of the cup.
A particularly elegant embodiment of the vertebral column replacement body is obtained if the tightening screw is formed by a headless screw which does not protrude above the threaded bore with its end provided for the slot for applying a screwdriver.
As mentioned above, the length of the range within which an infinitely variable adjustability of the spacing between the anchoring sides of the two body elements exists can be freely selected. For this purpose, the second cylindrically constructed body element has an oblong hole extending along its circumferential line, wherein a screwdriver can be placed through the oblong hole for acting on the tightening screw, and wherein the length of the oblong hole determines the extent of the possible height adjustment.
The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of the disclosure. For a better understanding of the invention, its operating advantages, specific objects attained by its use, reference should be had to the drawing and descriptive matter in which there are illustrated and described preferred embodiments of the invention.